Manufacturing method for a fused brushware device

Abstract: The molded component (200) which is tufted with filament tufts (205) has a configured one-piece construction having both chemical and physical properties which contribute to the straightness of the finished brushware (206) and result in the working ends of the tufts having the same configuration as the surface being cleaned.

Description: The invention relates to the manufacturing of fused brushware products. Many different types of brushware and methods for their manufacture have been devised over the past few centuries starting with ordinary tree and shrub branches, and developing into wire-set, anchor-set, staple-set, twisted-in-wire and resin-set designs including both natural and synthetic filament materials. Not until the method of fusing like materials, e.g. polypropylene monofilament onto a molded section of polypropylene, has the basic brushware configuration changed. Many U.S. Patents, e.g. Nos. 3,604,043; 4,189,189; 4,291,431; 4,348,060; 4,690,277; and 4,693,519 issued to John C. Lewis, Jr., disclose tufted fused brushes and mat like devices wherein synthetic filament tufts are fused to molded base sections. According to a first aspect of the present invention, there is provided a method of manufacturing a fused brushware device, comprising: determining a desired final shape for a tuft surface of the brushware device; molding a thermoplastic tuft base which includes the tuft surface, the molded shape of the tuft base being self-supporting and such as to give the tuft surface an initial shape which is convexly or concavely curved and is different to the desired final shape; and subjecting the tuft base to a single heating and cooling cycle during which (i) the tuft base is differentially heated so as to heat the tuft surface, (ii) filament tufts are fused to the tuft surface and (iii) the tuft base is permanently distorted by the differential heating and the cooling so as to distort the tuft surface from its initial shape to the desired final shape. The fusing process causes the tuft base (e.g. brushware block) to first expand (take a set or curvature) and, upon cooling, to shrink past its original (molded attitude) shape so that the tuft surface adopts the desired final shape. Because the working ends of the tufts will also generally have the desired final shape of the tuft surface, there is no need to trim the working ends of the tufts to make them conform to the shape of the surface that is to be cleaned. There is also no need to lengthen the manufacturing process by subjecting the brushware device to a second heating and cooling cycle which merely corrects the shape of the tuft surface. The components of the brushware device may be made from the same raw material, e.g. polypropylene resin, so as to be recyclable at some later time. There can be instances where there would be a need to fuse unlike materials, e.g. a polypropylene molded base with polyester monofilament tufts fused thereto. The brushware device may be a floor push broom, a bench brush or a nail brush. Blow molding may be used to form the base (brushware block). According to a second aspect of the present invention, there is provided a method of fabricating a fused brushware device, comprising: molding a curved thermoplastic block having a deflection ratio of 0.020 to 0.060 and a tuft surface with a first configuration which is convexely or concavely curved; subjecting said molded block to straightening prior to fusing whereby said tuft surface is given a second configuration; picking synthetic thermoplastic filament tufts, melting said tuft surface and fusing said filament tufts onto said tuft surface; and allowing said fused block to cool so that said tuft surface permanently distorts to a third configuration; whereby there results a fused brushware device wherein the working ends of said tufts also generally have said third configuration. Non-limiting embodiments of the invention will now be described with reference to the accompanying drawings, wherein:- FIG. 1 is a side view of an unassembled conventional single plane molded filament support block before fusing (prior art); FIG. 1A is a top view of the filament support block of FIG. 1 (prior art); FIG. 1B is an end view of the filament support block of FIG. 1 (prior art); FIG. 2 is a side view of the filament support block of FIG. 1 after fusing (prior art); FIG. 2A is an end view of the fused filament support block of FIG. 2 (prior art); FIG. 3 is a side view of the fused brushware of FIG. 2 when located under heating means (prior art); FIG. 4 illustrates the fused brushware of FIG. 3 after having been removed from the heating means (prior art); FIG. 5 is a side view of the fused brushware of FIG. 4 after cooling (prior art); FIG. 5A is an end view of the fused brushware of FIG. 4 (prior art); FIG. 6 is a side view of a configured molded filament support block prior to fusing according to the present invention; FIG. 6A is an end view of the pre-curved molded filament support block of FIG. 6; FIG. 7 is a side view of the block of FIG. 6 as located in a block holder device prior to fusing; FIG. 8 is a side view of the filament support block of FIG. 7 after fusing; FIG. 9 is a side view of the still-warm fused brushware of FIG. 8 immediately after removal from the block holder device; FIG. 10 is a side view of the cooled fused brushware of FIG. 9; FIG. 10A is an end view of the brushware of FIG. 10; FIG. 11 is a side view of a conventional molded filament support block for a bench brush (prior art); FIG. 11A is a cross-sectional view of the block of FIG. 11 as taken along line 11A-11A (prior art); FIG. 11B is a top view of the block of FIG. 11 (prior art); FIG. 12 is a side view of the block of FIG. 11 after fusing (prior art); FIG. 13 is a side view of a configured filament support block for a bench brush, prior to fusing according to the present invention; FIG. 14 is a side view of the block of FIG. 13 after fusing and cooling; FIG. 15 is a side view of a configured filament support block for a nail brush, prior to fusing according to the present invention; FIG. 15A is a top view of the block of FIG. 15; FIG. 15B is an end view of the block of FIG. 15; FIG. 16 is a cross-sectional view of the block of FIG. 15A as taken along line 16-16; FIG. 17 is a partially cut-away side view of the block of FIG. 15 after fusing and cooling; FIG. 18 is a side view of a molded brushware block illustrating a premolded curvature according to the present invention; FIG. 18A is a top view of the block of FIG. 18; FIG. 18B is an end view of the block of FIG. 18; FIG. 19 is a cross-sectional view of the block of FIG. 18 as taken along line 19-19; FIG. 20 is a side view of the block of FIG. 18 as located in a block holder device prior to fusing; FIG. 21 is a perspective view of the brushware block of FIG. 18 after fusing and cooling and after removal from the block holder device; and FIG. 22 is a perspective view of a pipe cleaning brushware configuration. Referring to FIGS. 1-1B, there is illustrated a polypropylene structural foam molded flat brushware block 100, comprising a top 101, ends 102, sides 103, a bottom or fusing surface 104 and a hole 105, said hole 105 having means for holding or attaching a handle device (not shown). When fusing polypropylene filament to said block 100 (simultaneously applying generally 150 to 200 plus individual filament tufts consisting of a group of prefused filaments), the entire bottom or fusing surface 104 is first pre-melted, and upon bringing the prefused filament tufts into contact with the surface 104 the melted and still viscous resin bonds the two components together, upon cooling. When the tufts 106 and the block 100 cool to room temperature, the first change in the plane of the original straight block 100 occurs when the bottom surface takes a convexed curvature and, as cooling sets in, the bottom comes to the original straight plane attitude, and then continues to warp and become concaved as FIG. 2 illustrates. This is explained by the fact that only the bottom surface 104 was heated; therefore, it first expanded, then as it cooled it returned to its original attitude, and then continued to go past by the amount "X" as illustrated in FIG. 2. A ratio can be determined from taking half the total length "Y" (or "Z") and dividing "Z" into "X" to arrive at a number which is generally in the range from 0.020 to 0.040 depending upon the type of molding employed and thickness of the molded parts. Measuring the amount of deflection along half the length "Z" from the original straight block, the amount of difference "X" becomes the significant deviation factor. Taking the ratio of "X" divided by "Z", one gets a figure that allows one to configure a pre-curved molded surface into a brushware block prior to ever experimenting or constructing a mold. Table 1 below illustrates the ratios for some polypropylene molded blocks. (MOLDED POLYPROPYLENE BLOCKS) "Z" "X" RATIO TYPE 23.8mm (0.937 inches) 0.889mm (0.035 inches) 0.0373 Injection Molded 60.3mm (2.375 inches) 1.397mm (0.055 inches) 0.0231 Injection Molded 76.2mm (3.000 inches) 4.801mm (0.189 inches) 0.0630 Injection Molded 177.8mm (7.000 inches) 6.350mm (0.250 inches) 0.0357 Structural Foam 228.6mm (9.000 inches) 6.985mm (0.275 inches) 0.0305 Structural Foam 304.8mm (12.000 inches) 10.160mm (0.400 inches) 0.0333 Structural Foam As shown in FIG. 2, the filament tufts 106 and their working ends 106' also take on the same curved distortion as the block surface 104, and consequently the brushware device 107 will not lie flat on a surface, e.g. a floor. FIG. 2A illustrates the "humping" of the block 100, i.e. the top surface 101 is visible in addition to the end 102. During the fusing process, it has been determined that the polypropylene molecules, which were oriented (crystalline) during the molding process, when reheated a second time contracted more on the fusing surface 104 of the block 100, than on the top surface 101, which was not heated. Essentially, due to applying approximately 427°C (800°F) to surface 104, and room temperature to the top surface 101, the result upon cooling is a curved out-of-plane brushware device 107. In order to straighten the brushware, i.e. broom 107, it becomes necessary to heat the top surface of the block 101 as illustrated in FIG. 3. The same heating procedure as before is applied to the top surface 101 with radiant heaters 108 and the heat 108' penetrates the top surface 101 of block 100. As this heat is applied, the top surface 101 actually expands, as illustrated in FIG. 4, and thus creates more curvature of the brushware 107. The deformation or deviation from "X" to (X') is evident on block 100 in FIG. 4 as shown. When the heat is removed and the brushware 107 is allowed to cool, it returns to the normal state of the unfused block 100 as shown in FIGS. 5 and 5A where the deviation (X') is basically zero, and the filament working ends 106' lie in a parallel relationship to the surface being cleaned. It normally requires ten minutes' heating time to complete this straightening procedure and an additional twenty to thirty minutes to cool the brushware down to room temperature. The illustrated embodiments of the invention are cosmetically correct and functional brushware because they use pre-configured molded blocks, as illustrated in FIGS. 6, 13, 15 and 18; these blocks only serve to illustrate what is possible. As described in the above conventional embodiment for fusing regularly molded brushware blocks, if the fused block is not post straightened, the resulting product will not perform. Turning now to the new and improved method of fusing brushware blocks, the pre-molded curve ratio [H/L] of FIG. 6 illustrates that the polypropylene structural foam block 200 has a concave top 201, raised end portion 202 and a convex bottom 203. When viewing block 200 from the end as in FIG. 6A, one sees that the bottom portion 203' can be seen directly under the end section 202. In order to fuse filament onto block 200, it first becomes necessary to mount the block 200 in a straightening fixture 204-204' as shown in FIG. 7. The bottom 203 of the pre-molded curved block 200 has been made to lie in a straight-line plane as illustrated by 203''. Ordinary fusing of polypropylene filament onto the flat surface 203'' of block 200 is shown in FIG. 8 and produces filament tufts 205, and when the fused broom 206 is removed from the straightening device 204-204' it immediately assumes the original pre-molded curvature profile as shown in FIG. 9 with the deviations H' from a flat surface plane. Upon cooling of the fused filament/block area 207 the block 200 of the broom 206 slowly contracts along the entire fused surface area, thus allowing the pre-molded curve to become straight as illustrated in FIGS. 10 and 10A. Figures 11, 11A, 11B and 12 illustrate an ordinary structural foam molded polypropylene block 300 which normally would be molded with a straight profile in order to staple-set filament tufts therein, and what will happen instead when filament tufts are fused thereon. The block 300 comprises a straight top section 302 and bottom section 301 and a straight portion of handle 303. The cross-section of FIG. 11A was taken through lines 11A-11A of FIG. 11. FIG. 11B illustrates the top view with top 302 and hang-up hole 304. When polypropylene filament tufts 305 are fused to the bottom surface 301, and allowed to cool as in FIG. 12, the block 300 becomes curved and has a deviation of "I". One should note that the handle section 303 does not become affected by the fusing process and remains straight. In order to fuse a straight brush 404, i.e. bench brush, it becomes necessary to first mold a configured structural foam block 400 as illustrated in FIG. 13 having a convexed fusing surface 401. The molded block, in this case, may include handle section 402, which is molded in a straight plane and, as in this embodiment, wants to remain straight in the finished fused brush 404. After fusing polypropylene filament tufts 403 to the curved surface of 401 of FIG. 13, the brush 404 of FIG. 14 becomes straight after a few minutes of cooling, and the pre-configured molding curve becomes straight. The above-mentioned embodiments of this invention were illustrations of structural foam molded blocks where the thickness of the blocks is generally in the order of 6.35 to 25.4mm (0.250 to 1.000 inches). Attention is now drawn to injection-molded blocks whereby the thickness range is generally from 1.27 to 6.35mm (0.050 to 0.250 inches). The small nail brush unit shown in FIG. 15 measures approximately 101.6mm (4 inches) long and 38.1mm (1.5 inches) wide and appears to have a thickness of 12.7mm (0.5 inches). A pre-configured curve has been molded into the block 500, having ends 505 and a straight parting line 503. FIG. 15A illustrates the top view and shows sides 504, ends 505 and a hang-up hole 502. FIG. 15B shows the end view of the block 500 with projections 501 extending downward from sides 504. The sides 504 only appear to have the projections and are, in fact, parallel sides of equal width. FIG. 16 illustrates the cross-sectional view of block 500 as taken through lines 16-16 of FIG. 15A and, as can be seen, the actual fusing portion (filament accepting surface) 507 has a bottom surface 507 and top surface 507'', each surface being precurved (convex for 507 and concave for 507''). After fusing polypropylene tufts to the surface 507 and allowing for cooling, the block 500 cools to a straight, parallel-sided nail brush 508 having a curved parting line 503 with a flat brush surface as illustrated in FIG. 17. There are some brush constructions, for example, brush 702 of FIG. 22, whereby it is advantageous to have the brush surface 701 configured in such a manner that it conforms to a given shape, e.g. for cleaning an ordinary pipe 703. In order to allow an internally radiating brush working surface to conform to a pipe s outside convex surface, it becomes necessary to construct a brush 702 arranged so that all of the working brush surface 701 touches and cleans the pipe s surface 704 at once, as illustrated in FIG. 22. The following embodiment will illustrate that, by molding a block 600 of FIG. 18 and deliberately configuring into the injection-molded block a predetermined curvature that will further contract when fused, the fused brush block working filament ends will lie congruent with the surface to be cleaned as well as exerting pressure thereon simultaneously. In FIG. 18, the block 600 has a fusing surface 601 adjacent to a top surface 602 and integrally connected to an extending threaded protrusion 603. The block 600 thickness J, in this instance, can be in the order of 2.03 to 3.81mm (0.080 to 0.150 inches). The FIGS. 18A and 18B illustrate the top and end views respectively, showing threaded hole 604 as molded into extension 603. FIG. 19 further illustrates a cross-sectional view of the integrally molded "curved" block 600 as taken through lines 19-19 of FIG. 18, and shows the thread 605 of hole 604. The concave surface 601 will be able to accept fused filament when the block 600 is affixed into a straightening fixture 606 as illustrated in FIG. 20. After fusing filament tufts onto surface 601 of block 600 and cooling is completed, the fused brush 608 is curved having a smaller diameter than the original molded block 600 and brush tufts 607 all converge toward the center of the brush construction 608. It should be noted that the desired tuft surfaces of the brush blocks of the embodiments of the present invention are generally flat or generally convex in only one direction. Thus, the brush tufts are generally parallel to each other or generally perpendicular to a focal axis. Obviously, many modifications and variations of the above embodiments of the instant invention are possible in light of the above teachings. The block may be made from polypropylene molded resin and fused synthetic polypropylene monofilament is the preferred tuft material. Other synthetic resins such as polyesters, polystyrenes, polyamides and the like may be employed. Filament diameters and cross-sectional shapes may also be varied, with diameters ranging from 0.127 to 1.27mm (0.005 to 0.050 inches) and cross-sectional shapes from circular, "X", "Y" and other shapes, thus imparting different cleaning attributes to the brush structure. The molded block may include rib or structural fin-like projections in order to reinforce the tufted surface without sacrificing the lightweight properties of the resultant brushware. There are unlimited brushware designs that can now be manufactured. Simultaneous picking and fusing of all the filament tufts can be achieved by practicing the instant invention.

Claims: A method of manufacturing a fused brushware device, comprising: determining a desired final shape for a tuft surface (203, 401, 507', 601) of the brushware device; molding a thermoplastic tuft base (200, 400, 500, 600) which includes the tuft surface, the molded shape of the tuft base being self-supporting and such as to give the tuft surface an initial shape which is convexly or concavely curved and is different to the desired final shape; and subjecting the tuft base (200, 400, 500, 600) to a single heating and cooling cycle during which (i) the tuft base is differentially heated so as to heat the tuft surface, (ii) filament tufts (205, 403, 506, 607) are fused to the tuft surface and (iii) the tuft base is permanently distorted by the differential heating and the cooling so as to distort the tuft surface from its initial shape to the desired final shape. The method of claim 1, wherein the tuft surface (203, 401, 507', 601) is elongate in the direction of a surface axis and the distortion of the tuft surface from its initial shape to the desired final shape involves substantially only a change of curvature along the surface axis. The method of claim 2, wherein the initial shape of the tuft surface (203, 401, 507') is convex along the surface axis and the desired final shape of the tuft surface is substantially straight along the surface axis. The method of claim 2, wherein the initial shape of the tuft surface (601) is concave along the surface axis and the desired final shape of the tuft surface is more concave along the surface axis than the initial shape. The method of claim 3 or 4, wherein during said heating and cooling cycle the tuft base (200, 600) is placed in a straightening device (204, 204', 606) which elastically deforms the tuft base so as to straighten the tuft surface, and the filament tufts (205, 607) are fused to the straightened tuft surface. A method of fabricating a fused brushware device, comprising: molding a curved thermoplastic block (200, 400, 500, 600) having a deflection ratio of 0.020 to 0.060 and a tuft surface (203, 401, 507', 601) with a first configuration which is convexly or concavely curved; subjecting said molded block to straightening prior to fusing whereby said tuft surface is given a second configuration; picking synthetic thermoplastic filament tufts (205, 403, 506, 607), melting said tuft surface and fusing said filament tufts onto said tuft surface; and allowing said fused block (200, 400, 500, 600) to cool so that said tuft surface permanently distorts to a third configuration; whereby there results a fused brushware device wherein the working ends of said tufts also generally have said third configuration. The method of claim 6, wherein said molded block (200, 400, 500, 600) and filament tufts (205, 403, 506, 607) are made of the same thermoplastic resin, resulting in a brushware device that is recyclable. The method of claim 6 or 7, wherein said third configuration is planar.

Inventors: LEWIS JOHN C, LEWIS, JOHN C.
Applicants: TUCEL INDUSTRIES, TUCEL INDUSTRIES, INC.
Application year: 1994
Main classification: A46D3
IPC codes: A46D3, A46D9